This invention relates to programmable logic integrated circuit devices (“PLDs”), and more particularly to input/output (transceiver) circuitry for use on PLDs.
PLDs are typically intended to be relatively general-purpose devices. This means that a PLD product is typically designed to be able to support any of a range of uses to which various users may wish to put the device. By enabling one PLD product to satisfy such a range of possible uses, the size of the market for the product can be increased. Increased sales volume can help lower the unit cost of the product.
Giving a PLD product a range of capabilities has a tendency to increase power consumption of the PLD. This can be a significant issue for some potential users of the product. Accordingly, it can be desirable to find ways to give a PLD product a wide range of capabilities and at the same time to reduce power consumption of the PLD, especially when certain of its capabilities are not needed by users who are concerned about power consumption. The input/output (transceiver) portion of a PLD can be especially subject to considerations of this kind. This is so because there are so many different communication protocols that it may be desirable to enable a PLD product to support. Certain aspects of being able to do this may significantly contribute to PLD power consumption. But potential users who are concerned about power consumption may not need the more advanced communication capabilities of the PLD, and so it would be useful to provide a PLD transceiver architecture that can be configured for either advanced communication or reduced power operation.